The present invention relates generally to electrical adapters, connectors and interface devices for interfacing testing equipment with units under test. More particularly, the present invention relates to an improved interface device for interfacing a unit under test (UUT) to a general purpose interface (GPI) of a diagnostic test station, such as a Consolidated Automated Support System (CASS) station.
The CASS diagnostic test system is a standardized suite of automated military electronics test equipment. It is designed to perform full electronics testing, in the nature of functional tests, calibration, and fault detection and isolation, on defense equipment electronic systems in aircraft, aircraft carriers, submarines and other land, air and sea military assets. Designed to solve problems of unreliability, rapid obsolescence and difficult logistic support, the CASS system provides modularity and flexibility to allow expansion for testing both current and future technologies. The CASS system is deployed in different locations, typically military aircraft electronics development and manufacturing centers, naval air stations and aircraft carriers. It is available in various different configurations, depending on the type of electronic defense equipment being tested.
Use of the CASS system typically occurs after onboard built-in test equipment (“BIT”) detects or “flags” a fault in a particular aircraft electronics system. The BIT is typically able to detect faults at the module level of the electronics system, known as the Weapons Replaceable Assembly (“WRA”). Failure data generated by the BIT advises service and maintenance personnel that a failure has occurred within a particular WRA and that testing and repair of that particular module is required.
The WRA modules are assemblies, typically having the external form of military-grade metallic boxes, each containing multiple removable printed circuit boards or cards, called Shop Replaceable Assemblies (“SRAs”). Between 5 and 45 such SRAs are typically located within a particular WRA. The detection of a failure in a selected WRA by an onboard BIT indicates one or more failures in one or more SRAs within that WRA. Although the BIT is occasionally able to detect faults beyond the WRA level to the SRA level, typically, the BIT is only used for fault detection at the WRA level. More precise fault detection at the SRA level is performed by removing the WRA from service and testing the electronic systems within that particular WRA at a CASS station.
The CASS station serves dual purposes in the testing of the WRA and SRA assemblies. First, the CASS station is able to test a WRA as a single electronic system (an intermediate level, or “I-level,” test), in greater detail than the BIT test. In particular, the CASS station testing of the WRA as a single electronic system identifies individual SRAs having defective electronic components. The CASS station is then also able to test the SRAs on an individual basis, to detect faults within the actual electronic components making up a particular SRA, such as chips, integrated circuits, resistors, capacitors, etc. (commonly referred to as the “piece parts”). Typically, the CASS station testing is able to identify a small group of individual components (perhaps 5 to 7) or “piece parts,” and sometimes a single component, within a particular SRA that is defective and therefore in need of replacement.
Thus, the overall method for repairing detected WRA failures using a CASS station involves first testing a WRA as a single system to determine defective SRAs, removing any defective SRAs from a particular WRA, testing these defective SRAs individually to detect individual defective components, replacing the defective components and reinstalling the repaired SRAs within the WRA. Since the WRA modules are typically removable by hand by disconnecting them from the wiring system of the particular military asset involved, they can be brought to a CASS station for diagnosis, repaired as needed and then reinstalled in the military asset.
Because the CASS system is intended to be a universal testing system for many different types of electronic components, it includes a universal-type electrical-mechanical interface in the nature of a GPI. The GPI is a vertical panel on the front of the CASS station containing over 1400 (typically gold-plated) connection pins of three primary types: (1) power pins, which handle high current, and are typically relatively expensive; (2) small signal or small amperage pins, which are less expensive; and (3) coaxial or “coax” pins, which are relatively expensive.
The CASS station GPI pins are referred to as “female” connectors, which engage a plurality of sockets organized in the form of a connector box, or “interface device” (“ID”) that is attached as the “male” connector set onto all or part of the CASS station GPI. The ID is used to provide electrical and mechanical connection between a UUT, which may be a WRA or an SRA, and the 1400+ pins of the CASS station GPI. The individual WRAs removed from military assets for CASS station testing typically include three to five “male” socket connector assemblies typically having between about 10 to 120 sockets that are connected to the CASS station GPI pins in a particular arrangement to accomplish the desired testing functions.
Typically, the ID includes “floating” GPI contacts to prevent bending and premature failure of the contacts. That is, the GPI contacts of the ID are held in their respective connector boxes or connector bodies such that they are moveable axially and/or radially to a small extent, to facilitate mating with connector pins of the CASS GPI, which reduces instances of damage to the pins (e.g., by bending or breaking) during mating.
Conventionally, the ID devices utilize discrete wiring. While discrete wiring permits floating of the ID's GPI contacts, discrete wiring produces variations during manufacture that must be eliminated during validation of the device. Such validation is labor and capital intensive, because both the CASS station (or other automatic test equipment) and a troubleshooter are required. Wiring faults may also include subtle errors, such as inappropriate routing for unshielded conductors, resulting in crosstalk. These and other problems caused by discrete wiring may not exhibit themselves during validation or are induced by shipping stresses, so they become “field failures” that may require costly travel to a customer site and, in any case, result in customer perceptions of poor quality. Moreover, discrete wiring increases part count and fabrication effort, and also makes repeatability (i.e., consistency in performance and operation from device to device) extremely difficult.
In general, the use of a printed wiring board (PWB) provides high reliability and repeatability with reduced production cost. Although the simplicity, reliability and repeatability of a PWB would make the use of PWBs preferable over discrete wiring for the reasons stated above, PWBs have not been used in IDs because the GPI contacts of the ID must be permitted to float and cannot be constrained by attachment (e.g., by soldering) to a rigid member such as PWB. The benefits of a PWB based design have resulted in some GPI contact to PWB connection schemes involving at least some small length of wire (to permit floating of the GPI contacts of the ID), but even such small lengths of wire are undesirable because they result in many of the same problems caused by discrete wiring schemes.
Thus, there is a need to replace discrete wiring in the ID with a PWB, without constraining or otherwise interfering with the floating of the ID's GPI contacts, and without inhibiting overall performance and reliability of the device.